The CBS News/New York Times survey found Clinton had just a two-point edge (46 to 44 percent) over her Republican rival in a two-way matchup among likely voters. Among registered voters, the Democratic nominee was five points ahead, at 46 to 41 percent.

When third party candidates Gary Johnson and Jill Stein were included, the race was tied among likely voters -- at 42 percent each -- while Clinton had a slight edge (41 to 39 percent) among registered voters.

A Quinnipiac University poll out a day earlier, on Wednesday, found that results were too close to call when third party candidates were included, with Clinton at 41 percent and Trump at 39 percent.

The CBS/NYT poll also found diminished voter enthusiasm, with Democrats less enthusiastic about voting now than a month ago, while Republicans have kept a steady level of enthusiasm.

A total of 64 percent of registered Democratic voters said they felt at least somewhat enthusiastic about voting -- a drop from 77 percent in August -- and just 38 percent said they were very enthusiastic, down from 47 percent a month ago.

Trump voters specifically were more enthusiastic than those supporting Hillary -- with 45 percent of the billionaire real estate investor's backers saying they felt very enthusiastic about voting, compared to 36 percent of the former top US diplomat and first lady's supporters saying they felt that way.

Among Republicans, 43 percent said they were very enthusiastic, and a total of 68 percent said they felt at least somewhat enthusiastic.

And a gender gap is still apparent between the two candidates, with Trump securing a double-digit lead ahead of Clinton among men, while she has a similar margin over him among women.

Trump faces continued struggles to gain support among African American voters, though he has an advantage over Clinton among whites.

White voters lacking a college degree gave Trump a strong show of support -- 58 percent -- while Clinton led Trump among white college graduate voters.

Among white college graduates, only 29 percent backed Trump, 48 percent supported Clinton, but 21 percent said they would vote for someone else or stay out of the polling stations come Election Day, on November 8.